The holes are countersunk with a rounded circumference eliminating the stress points usually associated with drilling. When Summit Point opens for track-days again I’ll see how the rotors do.

 

It has been a long while since I took material science class, but the above explanation does not make sense to me. It is the process of drilling and heat generated by the drill that changes metal structure around the hole that leads to development of stress cracks. That and a natural weak point due to a hole.

 

Fairly basic concept: rounded (chamfered) edges relieve stress points.

 

Agreed. When repairing cracks in armored hulls of MRAPs, we drill holes at the ends of the crack to stop it from spreading. Then we weld the crack closed. Of course there are very specific temperatures that are constantly monitored and cool down times between applications dependant on size and time of welds. Our approved procedures do not affect the molecular structure of the armored steel if done correctly.

 

I don't think the OP's problems stemmed from the brake rotors themselves. There may have been a secondary issue with the rotors, but not the direct issue. The R4-S pads were the main cause of the issues. However, the OP mentioned that he still had some problems (not as bad) after replacing the OEM pads. Likely what happened here is that the R4-S transfer layer was already deposited on the rotors. The OEM pads are probably not abrasive enough to quickly remove the R4-S transfer layer thus making the OEM pad not as effective as it should have been. Replacing the OEM rotors that already had the OEM brake pad transfer layer on would have likely made things better but I don't believe the rotors themselves were the blame for any of the issues. i.e. OEM brake pads with the StopTech rotors would have likely been just as effective as OEM rotors and OEM pads. Just note that sometimes the slots can cause additional wear on brake pads.

 

I am with the group of people suspicious that something is not OK. By design if everything is OK your brakes will very unlikely behave like the OP says.
Also, Stoptech is not "cheap" brake company, do you have any data supporting that? They have superiour cooling than OEM, they do 2piece aero rotors, BBKs... They are not AP racing level but overall its a legit company. From my previous "car club" dozens of people have them from rotors and pads to BBKs without any issues. Even their competitors was saying all is OK with them.
I have no experience with Portefield, but two laps to no brakes should not be an issue to any performance pads to be honest. Especially when so much people here have tham. Saying that you NEED racing pads for a few laps on track is crazy.

 

Perhaps I should rephrase. Rather than cheap, they are designed for low cost. A set of 4 for the F-Type can be had for ~$500. If the OP acquired that version, I still suspect they are at the root of the overheating.

 

I'm curious. Given the function of the rotor, what part of the overheating issue to you believe they contribute or are the direct cause?

 

I suspect the ribbing within the internal void of the rotor is not designed as well as the OEM rotor to ensure good dissipation of the heat.

 

I'm assuming you are referring to the internal veins. There is no real technical design of those (i.e. between different vendors), and Stoptech knows their stuff. However, I could see a mis-installation where the installer didn't have the veins rotating in the proper direction.

 

The total of the rotors was about $1,050. I believe they were installed correctly (directionally) and the shop GM QA’d the install himself to confirm the directional install.




Also, for general forum interest, here’s the OEM pads post track day (same general temp, probably 2 hours total on track) vs. the R4-S. I bedded both pads in, but could very well have messed up the R4-S on these new rotors.





Talking again with the shop GM we’re trying to best decide whether to go back to OEM rotors with track pads or the Wortec front kits + back rotors w/ OEM calipers and track pads. The alternative, which unfortunately might end up being the case, is just picking a different platform to track vs. the SVR.

 

IMO, unless you just want the looks, stick with the OEM rotors. There is nothing wrong with them. Focus on the brake pad. You can track the F-Type. If you have the money to have a dedicated track car and keep the SVR, there are better dedicated track cars out there. However, the SVR can be a great dual purpose car if you pick the proper changes.

 

That’s what I’m trying to dial in. What I was previously looking for:

1. Brake kits [This thread]
2. AIM Solo 2 & Smartycam [INSTALLED]
3. Steering wheel change (wanted flat bottom to try and give more legroom; I’m unable to left foot brake right now due to tallness) [ORDERED]
4. 5-point Harness (still trying to figure out how to get this done)

Happy to hear other suggestions to make this better on track. It’s not my daily driver, so open to suggestions.

 

Rule of thumb, any dedicated track pad is not going to be great for the street (i.e. won't get hot enough to grab well and could squeak). I believe someone mentioned that VAP can special order R4 pads. I don't know for sure, but it's possible the brake pad size matches another JLR model which means there could be more options available as well.

When you had everything OEM, did you experience brake fade / brake overheating?

 

Yep, Porterfield DO make the R4 pads for the F-Type (except for the 355 mm front brakes), see post #7 in this thread.

 

Yes, a little fade but no glazed pads and no overheated brake warnings. I was trying to fix the fade.

As it stands right now, I'm thinking about returning to the OEM rotors and trying the R4 pads. I was hoping to be able to save some weight with lighter rotors, but she's heavy regardless.

 

That would be my recommendation. However, I've never use the R4 pads so I don't know if they are usable on the public streets. You might have to switch pads in/out for track duty.

 

You didn't ask about this, but a FYI

The rim in the picture has excessive amount of balancing weights, it probably has to be re-manufactured to fix it or better balancing machine used. Also, these glue-on balancing weights are not suitable for the track - under heat glue comes undone and they come flying off.

If this tire was installed by a racing shop you use to install your brakes - they don't know what they are doing. If they didn't mention it to you after working on brakes - they don't care.

 

JLR dealership put on the tires. The race shop didn't mention anything. I had no clue what those were. I guess I can ask them to remove them and realign or re-sit the wheels next time in?

Thanks for the information, another thing for me to read up on.

 

Worse yet, there are outside balancing weights on opposite sides of the wheel circumference. Makes no sense whatsoever. Absolutely counterproductive.


They need to be removed and the wheel/tire assembly rebalanced.